Installation fails on macOS with recent Homebrew changes

[mtl1979]

Homebrew 6.0.0 was released few hours ago, but even after upgrading Homebrew, we still get this error message:

Error: Refusing to load formula coverallsapp/coveralls/coveralls from untrusted tap coverallsapp/coveralls.
Run `brew trust --formula coverallsapp/coveralls/coveralls` or `brew trust coverallsapp/coveralls` to trust it.
Failed to install coveralls via Homebrew (macOS).
Error: Process completed with exit code 1.

[afinetooth]

Thanks, @mtl1979. We'll check it out.

[afinetooth]

What happened

Homebrew 6.0.0 (released today, June 11) made a breaking security change: third-party taps are no longer loaded until the user explicitly trusts them, because a tap is arbitrary unsandboxed Ruby that runs with user privileges. Official Homebrew taps stay trusted by default; everything else — including coverallsapp/coveralls — now refuses to load until trusted. There is nothing wrong with the tap, but nothing the tap itself can do to mark itself trusted (that would defeat the purpose). Trust is granted on the client, in one of three ways:

• brew install <user/repo/formula> — a fully-qualified install auto-trusts just that formula
• brew trust --formula <user/repo/formula> — trust one formula
• brew trust <user/repo> — trust the whole tap

The fix

We will fix this in the Coveralls GitHub Action (this repo) asap since it is the "client" in this scenario, automatically installing the Coveralls Homebrew Formula when it recognizes CI runners running macos.

Until that's ready, here is a workaround:

Workaround

Immediate workaround for users with issue #264
Users who can't wait for the new release of the Coveralls GitHub Action (or who pin exact versions) can add one step before the action in their workflow:

- name: Trust Coveralls Homebrew tap (Homebrew 6 requirement)
  if: runner.os == 'macOS'
  run: brew trust coverallsapp/coveralls
- uses: coverallsapp/github-action@v2

[afinetooth]

Open PR for fix here:
#265